[Coral-List] Parrotfish and coral

Pedro M Alcolado gmalcolado at gmail.com
Fri Feb 24 15:59:47 EST 2017

Maybe the patogen appeared in Panama area and then dispersed along the
Caribbean without   being active in the whole Caribbean during a
while, until probably the arrival of the African dust (with nutrients
or another activating factor?) in a synergical way supposedly
triggered in some way the appearance of the Diadema disease in the
whole area (maybe a crazy asumption of mine!, if so, sorry!).

On 2/23/17, Douglas Fenner <douglasfennertassi at gmail.com> wrote:
> Gene,
>     Thanks!  As for African dust being the cause of the Diadema dieoff
> throughout the Caribbean and Florida in 1983, there is one detail of the
> dieoff that I wonder if African dust can explain.  The dieoff began in
> Panama and took an entire year to move around the Caribbean.  The sequence
> it moved in matches the direction of current patterns.  At individual
> locations, the dieoff took only about 10 days.  How can African dust
> possibly account for that pattern?  Did African dust first hit Panama, and
> then move around the Caribbean following water current patterns?  Why
> wasn't the dieoff synchronous across the Caribbean, and why was the dieoff
> complete at one location long before it even appeared at another?  Is there
> documentation of the African dust reaching the Caribbean in that pattern?
> Wouldn't the dust reach the eastern islands of the Caribbean and then move
> west?  Isn't that the direction that the wind usually moves?  That's how
> the dust gets from Africa to the Caribbean.  How could African dust get to
> Panama first before reaching the windward islands in the eastern Caribbean
> many months later??
>    Cheers,  Doug
> On Fri, Feb 17, 2017 at 8:49 AM, Eugene Shinn <eugeneshinn at mail.usf.edu>
> wrote:
>> Thanks to all who have weighed in and posted comments on the subject of
>> parrotfish herbivory, ancient fishing, and coral growth. I learned a
>> lot. The paper by Cramer, K. L., (2013) /History of human occupation and
>> environmental change in western and central Caribbean Panama,/ /Bulletin
>> of Marine Science /89m (4) 955-982 Is an outstanding read. The paper is
>> well documented, and shows how heavily populated central America was in
>> pre Columbian times before the Spanish came and obliterated more than 90
>> percent of the population. And yes, they did eat fish but most of the
>> damage to coral reefs then as now was mainly related to agriculture and
>> runoff. To feed fish to the once large population using only fish hooks
>> made from turtle shell still seems a bit of a stretch, especially
>> herbivorous fish. How does one bait a hook with algae? Most likely the
>> ancients used spears and nets along with fish traps. Traps are easy to
>> construct from native materials and such traps are still made and used
>> today in various parts of the Caribbean. Traps will certainly capture
>> parrotfish while even modern metal fishhooks seldom catch these fish.
>>       Other postings point out that parrotfish remove algae on dead
>> coral or other surfaces thus preparing the surface for coral
>> recruitment. This has long been the accepted standard explanation and
>> surely applies in many areas.
>>       Hanna Rempel (off line) pointed out that indeed certain parrotfish
>> do bite live coral. I agree and have watched them doing so. I once spent
>> a day on Looe Key reef watching parrotfish taking bites from large
>> Montastraea heads. It was an especially calm day and there were small
>> piles of parrotfish poop resting on the tops of several live coral
>> heads. Unfortunately I was not there long enough to watch for an effect
>> the defecated sand might have on the coral. Of course waves eventually
>> swept the sandy material off or the coral polyps removed the sand. What
>> was obvious, however, were many 3 to 5 cm dead spots supporting algae
>> and/or infected with black band disease. Bite marks suggested that
>> parrotfish made these areas. I had never seen parrotfish bites in
>> infected with algae before. Possibly there was an overabundance of
>> parrotfish because the reef is protected.
>>       Now back to my earlier comments concerning Carysfort reef in the
>> Florida Keys. I have been taking serial photos there for the past 56
>> years. Three summers ago I spent a day there with Phil Dustan who had
>> done the most significant monitoring work there in the 1970s when it was
>> a beautiful live /Acropora/ reef. At Carysfort all the /A. palmata/ and
>> virtually all the backreef /A. cervicornis/ was dead and had been
>> converted to rubble. Parrotfish were have a field day. They were biting
>> coral that had died back in the mid 1980s. There had been virtually no
>> recruitment there in the 30 or more years since. At the rapid rate the
>> parrotfish and roving bands of blue tangs are munching the dead coral an
>> abundance of reef sand has been created. That reef sand no doubt
>> contains fish teeth. Now spring ahead a hundred years and assume the
>> coral are flourishing and take some cores of the reef. Where would the
>> parrotfish teeth be? Would they not be in the sediment associated with
>> the period of time when the reef was dead and plenty of algae to eat? If
>> you counted the abundance of the teeth in the sandy part of the cores
>> would you conclude the parrotfish had killed the reef? Or would you
>> assume the fish died thus causing the corals to die? Or was it
>> pollution/disease/or climate change or something else, possibly African
>> dust that killed the reef?
>>       That parrotfish herbivory is not needed to stimulate coral reef
>> growth has been shown by others, Auchley A. McField MD. Alverez-Filip L.
>> (2016) /Rapidly increasing macroalgal cover not related to herbivorous
>> fishes on Mesoamerican reefs/. PeerJ 4:e2084
>> <https://doi.org/10.7717/peerj.2084>their observations on the Belize
>> reef tract are well documented.
>>       Kauffman has suggested hurricanes might kill and cause rubble to
>> become algal infested. That could also lead to parrotfish increases.
>> That event was well documented in Jamaica.
>>        When hurricane Donna decimated Grecian Rocks reef in 1960 the
>> reef did not become algal infested. In fact most broken fragments of
>> branching corals began growing and the reef area expanded. We documented
>> the storms effect. (Ball, et al 1967), and the recovery (Shinn 1976).
>> The same happened in 1965 when Betsy decimated the same reef. Again the
>> reef recovered. However, the reef did not recover after 1990 when
>> hurricane Andrew swept though the upper keys. Something had changed and
>> algal infestation became rampant. There were no longer /Diadema/ to
>> remove the algae (they had died in 1983) but there were sill abundant
>> parrotfish. Some time ago I proposed that the 1983 increase in algal
>> turf was related to the Caribbean-side demise of /Diadema/ and the
>> effects of African dust. (Lessios, et al 1984) had shown that /Diadema/
>> demise was Caribbean-wide. Monitoring of African dust by Joe Prospero
>> showed the dust had blanketed the Caribbean in 1983; He had been
>> monitoring dust in the eastern Caribbean since 1965 and showed 1983 to
>> be the peak year of dust flux to the Caribbean. (Shinn, E. A. Smith, G.
>> W., Prospero, J. M, Betzer, P., Hayes, M I, Garrison, V. Barber. R T.,
>> 2000, /African dust and the demise of Caribbean coral reefs/: Geological
>> Research Letters, v. 27, P. 3129-3132). Many will say it was sewage and
>> increasing population in the Keys that cause demise. However that does
>> not explain why the same events were happening simultaneously to reefs
>> around small islands throughout the Caribbean. Dust flux remains high
>> and a recent unfunded and unpublished preliminary testing of African
>> dust collected from the air showed it to be lethal to A/. cervicornis/.
>> Why it is toxic is not known but our earlier work at USGS showed that in
>> addition to the nutrients iron, and phosphate, the dust coincidentally
>> contains (copper, mercury, arsenic, radiogenic beryllium 7, lead 210,
>> various pesticides, and approximately 200 viable species of bacteria and
>> fungi) Possibly some of these ingredients can affect coral growth. But
>> that's another story. Hopefully some day someone will do the work needed
>> to determine exactly what is in the dust that affects coral and people)
>> but do not expect any government agency to fund the research. Everyone
>> who has written a proposal to do so has been turned down. Is more study
>> needed? You bet! Gene
>> No Rocks, No Water, No Ecosystem (EAS)
>> ------------------------------------ -----------------------------------
>> E. A. Shinn, Courtesy Professor University of South Florida College of
>> Marine Science Room 221A 140 Seventh Avenue South St. Petersburg, FL
>> 33701 <eugeneshinn at mail.usf.edu> Tel 727 553-1158
>> ---------------------------------- -----------------------------------
>> --
>> No Rocks, No Water, No Ecosystem (EAS)
>> ------------------------------------ -----------------------------------
>> E. A. Shinn, Courtesy Professor
>> University of South Florida
>> College of Marine Science Room 221A
>> 140 Seventh Avenue South
>> St. Petersburg, FL 33701
>> <eugeneshinn at mail.usf.edu>
>> Tel 727 553-1158
>> ---------------------------------- -----------------------------------
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> --
> Douglas Fenner
> Contractor for NOAA NMFS, and consultant
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